Lattice for the reinforcement of tubular concrete elements

ABSTRACT

A tubular lattice reinforcement for a reinforced tubular element having a socket, said lattice having longitudinal wires and transverse wires welded to said longitudinal wires, the transverse wires being bent and welded in the form of rings, said lattice extending throughout the length of the tubular element, the transverse wires in one end portion of said reinforcement corresponding to the socket of the tubular element.

United States Patent 91 Francois Mar. 18, 197

[54] LATTICE FOR THE REINFORCEMENT OF 2,571,578 /1951 Maelen l38/l75 X3,437,114 4/1969 Whitacre et al, l40/l l2 TUBULAR CONCRETE ELEMENTS [75]Inventor: Maurice Francois, Saint Dizier,

France Primary Examiner.lerry W. Myracle Attorney, Agent, orFirmSughrue, Rothwell, Mion, [73] Assignee. Trefllumon, Paris, FranceZinn & Macpeak I t I [22] Filed: Oct. 17, 1972 [21] Appl. No.: 298,321

Related 0.5. Application Data [57] ABSTRACT [60] Continuation of Ser.No. 109,424, Jan. 25, 1971, A tubular lattice reinforcement for areinforced tubug sgi "g g' g i g g' zgg gg 808252 lar elenient having asocket, said lattice having longitudinal wires and transverse wireswelded to said longitudinal wires, the transverse wires being-bent andwelded in the form of rings Said lattice extending [58] Fieid 52/6throughout the length of the tubular element, the 52/669 transversewires in one end portion of said reinforcet ment corresponding to thesocket of the'tubular ele- [56] References Cited ment UNITED STATESPATENTS 1 Claim 4 Drawing Figures 860,400 7/1907 Maag 138/175 x a 3 i3 0it L .k I T 12 LATTICE FOR THE REINFORCEMENT OF TUBULAR CONCRETEELEMENTS This application is a continuation of my prior copendingapplication Ser. No. 109,424 filed Jan. 25, l97l now abandoned, which inturn was a division of my copending application entitled Lattice for thereinforcement of tubular concrete elements having a socket, method forproducing said lattice and the products obtained, Ser. No. 808,252,filed Mar. 18, 1969 now US. Pat. No. 3,578,036 granted May 11, 1971.

The present invention relates to lattices of welded wires for producingreinforcements for concrete tubular elements having a socket and to thereinforcements and to concrete tubular elements comprising a section ofsuch a lattice.

It is already known to employ a lattice for reinforcing concrete tubularelements including a socket. However, the cross section of the socket issubstantially greater than that of the run or body of the tubularelement and the best steels do not have sufficient elongationcharacteristics to permit a large expansion without fracture. Thus, toproduce a reinforcement in one piece, there are at present two knownmethods:

The first consists in avoiding the reinforcement of the socket, thelattice being limited to the body of the tubular element; however, thesocket then has a strength which may be insufficient in some cases.

The second method consists in producing the reinforcement in two parts,namely one part for the run or body of the tubular element and a widerpart for the socket, the two parts being interconnected by metal wires;however, this method is relatively long to carry out and sometimesdelicate owing to the difficulties of centering the part of thereinforcement intended to be embedded in the socket.

The object of the present invention is to overcome these drawbacks.

The invention provides a lattice of welded metal wires wherein a numberof the warp wires have successive deformed non-rectilinear portions, thedeformations of said portions being permanent and such that, uponexertion of tensile stress thereon, said portions can be at leastpartially straightened, whereas the other warp wires and all the weftwires are rectilinear.

Owing to their deformed portions, which may form folds, waves, fractionsof a coil or any other sinuosities or convolutions, it is possible toelongate the corresponding warp wires and the lattice can undergo, inthe portion pertaining to these wires, an expansion in the direction inwhich the wires extend.

Other objects of the invention are to provide:

a pre-reinforcement obtained from a section of the aforesaid lattice andwherein some of the transverse wires have, starting from one of the endsofthe reinforcement and on a portion of its length, a succession ofpermanently-deformed portions so that the apparent perimeter ofsaidtransverse wires is equal to the perimeter of the other undeformedtransverse wires, but a real length substantially greater than saidperimeter;

a reinforcement having a socket obtained by means of the aforementionedmethod, said lattice reinforcement having transverse wires bent andclosed onto themselves in the form of welded rings and wherein, in thezone of the socket, the transverse wires of the lattice have a trace ofpartially open deformations;

and a tubular reinforced concrete element having a socket comprising alattice reinforcement which extends throughout the length of the bodyand has in the zone of said socket transverse wires which have a traceof partially open or straightened deformations; said tubular concreteelement being reinforced by means of a single-piece reinforcement whichextends into the whole of the socket.

Further features and advantages of the invention will be apparent fromthe ensuing description with reference to the accompanying drawing.

In the drawing:

FIG. 1 is a diagrammatic view of a plane section of lattice according tothe invention;

FIG. 2 is a perspective view of the same section of lattice after havingbeen bent and welded so as to form a closed cylindrical cageconstituting a prereinforcement;

FIG. 3 is a diagrammatic perspective view of the final reinforcementembedded in a concrete pipe having a socket, and

FIG. 4 is a diagrammatic perspective view of a modification of thereinforcement for a tubular body having an oval cross section includinga flat portion.

Reference will first be had to FIG. 1 which shows a section of animproved lattice according to the invention.

This lattice comprises a series of warp wires 1 and 2 and a series ofweft wires 3. The wires of the two series intersect at a right angle andare welded together at the crossing point 4. Whereas the warp wirescarrying the reference numeral 1 and the weft wires 3 are rectilinear,the warp wires 2 are deformed in alternately opposite directions so asto have successive non-rectilinear portions, either in the form ofcorrugations as shown, or in the form of folds, loops or othersinuosities or convolutions located in the plane or outside the plane ofthe lattice.

The deformed portions can be continuous, as shown, or interrupted byshort rectilinear portions.

The shape of the convolutions, corrugations or other deformations of thewires 2 is so arranged that their amplitude corresponds to the width ofthe electrodes of the welding machine employed for welding the lattice,since the warp wires and the weft wires are welded at the crossingpoints.

This shape is also chosen as a function of the total elongation ratecorresponding to the necessary expansion.

The same is true as concerns the choice of the steel of the corrugatedwires 2 whose elongation characteristic must be considered as a functionof the required expansion.

Now, let it be assumed that it is required to construct a reinforcementfor a concrete tubular element T having a socket e (FIG. 3). There iscut from the lattice according to the invention a section A (FIG. 1)whose dimensions correspond to the those of the reinforcement to beembodied in this pipe or tubular element T. This section can be cut atthe site of construction of the pipes from a roll of lattice or in afactory and delivered to the site in the flat condition.

This section has, in the direction of the weft wires, I

the desired length for the reinforcement, whereas in the direction ofthe warp wires, 1, 2 it has a length equal to 11' d, in which d is thedesired diameter of the body of the reinforcement, that is, the partwhich-is not the socket part (FIG. 2).

The section A of lattice is bent and welded in the form of cylindricalblank or pre-reinforcement B (FIG. 2). In this pre-reinforcement B thewarp wires 1 and 2 become transverse circular rings 1" and 2", whereasthe weft wires 3 remainrectilinear and embody generatrices of theresulting cylindrical pre-reinforcement B. In

this pre-reinforcement B, the rings 1 and 2 have a diameter d roughlycorresponding to the mean diameter ab of the wall of the body of theconcrete pipe T to be obtained.

Note that the rings 2" formed by the corrugated wires 2 have an apparentperimeter 1r d which is equal to the perimeter of the rings 1 formed bythe wires 1 but a real length which is substantially greater than thisperimeter owing to their convolutions, corrugations or othernon-rectilinear portions.

When employing this pre-reinforcement B benefit is had of the existenceof these corrugated portions of wires 2, which constitute a sort ofreserve of wire length, so as to restore this reserve by expansion ofthe rings 2" and afford larger rings 2" (FIG. 3), the diameter D of therings 2" corresponding to the mean diameter of the wall of the socket eof the pipe and beingsubstantially greater than the initial diameter dwhich corresponds to the diameter of the rings 1 since the socket of aconcrete pipe has a cross section which is greater than that of the bodyof the pipe.

In order to change from the cylindrical prereinforcement B shown in FIG.2 to the'final reinforcement C shown in FIG. 3, the pre-reinforcement Bis mounted on an expanding machine for expanding the rings 2". Thisexpansion is achieved by means of a known apparatus, such as anexpansible mandrel controlled by hydraulic, pneumatic or mechanicalmeans and inserted in the rings 2.

By means of this apparatus, only the corrugated rings 2' are expandedand undergo both a mechanical cirbodied in the concrete. The pouring canbe carried out in a static mould or in a centrifugal casting mould.

Thus, it will be understood that the shape and amplitude of theconvolutions, sinuosities, corrugations folds or other deformations ofthe wires 2 must be such that the sum of the intrinsic elongation of thewires 2, due to the characteristics of elongation proper to these wires,and the elongation of restoration" due to the straightening of thedeformations, allows an amplitude of expansion of these wires 2 which issufficient to produce, without fracture, a reinforcement for a sockethaving a diameter D substantially greater than the diameter d of thebody of the armature.

In view of the fact that for practical reasons the length of wire put inreserve in the deformations is nonetheless limited, the steel of thewires 2 is selected from a quality having an intrinsic elongationcharacteristic which is sufficient to obtain the expanded perimetercorresponding to the socket of the pipe T after adding the elongationdue to the straightening of the deformations. This steel may be, forexample and not exclusively, a SIEMENS-MARTIN steel or an oxygen-blownsteel.

cumferential elongation owing to the straightening of the corrugationsor other deformations and an intrinsec elongation, that is an elongationin the fibres of the metal. Owing to the restoration" of the excesslength of the corrugations, which were as it were put in reserve in theinitial lattice, the total elongation of the rings from 2 to 2" can beconsiderable and in any case substantially greater than the intrinsecpossibilities of elongation of uncorrugated wires.

The longitudinal wires 3 are also expanded near their ends in theconnection zone 4 between the expanded part and the non-expanded part.However, this connection zone 4 is of short length so that the naturalor intrinsec elongation of the wires 3 is sufficient to'permit thedeformation. 3

In this way, the final reinforcement C shown in FIG. 3 is obtained. Thisreinforcement comprises a number of longitudinal wires 3 embodying thegeneratrices of the reinforcing cage, a large number of non-expandedcircular rings 1" of uncorrugated wire and, in the zone of the socket, asmall number of rings 2" of wire which is still more or less deformed,the corrugations, folds or other convolutions not having completelydisappeared upon the expansion.

Finally, in order to obtain the reinforced concrete pipe T, thisreinforcement C is placed in a mould into which the concrete is poured.The reinforcement is em- Note moreover that although the uncorrugatedwires of the rings 1 and of the generatrices 3 may be bright wires, thatis to say, wireshardened by drawing, since they are not intended to beelongated and their elongation characteristics before fracture can below, the wires 2 may be of a steel having higher characteristics ofelongation before fracture and preferably, but not exclusively,non-aging.

Owing to the initial deformation of the wires 2 in the form ofsinuosities, convolutions, corrugations or folds, it is possible toelongate them to a substantially greater extent than would be permittedby the intrinsic elongation characteristics of these wires whenuncorrugated. Consequently, it is possible to manufacture in one piece areinforcementfor a concrete pipe having a socket by a large expansion ofthe part of the prereinforcement B corresponding to the socket zone ofthe pipe T intended to be'reinforced.

Thus, owing to the invention, it is possible to construct areinforcement in one piece, which is quicker to produce and employ thanknown reinforcements in two pieces which are interconnected. Thisone-piece reinforcement can be more easily bent than reinforcements intwo pieces in the mould for the concrete element or pipe.

Further, instead of transporting the reinforcements to the place ofmanufacture of the concrete pipes, in the pre-fabricated form, which isspace consuming and liable to damage the reinforcements in the course oftransport, the simplicity of the method according to the inventionenables the reinforcements to be constructed on the site, from rolls orpanels of lattices which are easy to transport with the minimum of spaceconsumption.

The numerical examples of the following table show the substantialincrease in the possibilities of elongation of the lattice wires, owingto the length of wire which is put in reserve in each corrugation andrestored by straightening.

This table shows the results of statistics established from many sampleshaving undergone tensile stresses The samples were plane lattices ofsteel wires having a diameter of 3.90 mm; the deformed wires hadsinusoidal corrugations whose pitch or wave-length was 30 mm and whoseamplitude was of the order of mm.

As can be seen, the gain in total elongation obtained with bright wireowing to the corrugations is increased by 25 percent in absolute value.Its relative value is considerable since it is multiplied by about 6.

The gain in the elongation due to the corrugations with annealed wire isbetween 21 and 25 percent in absolute value. It is less in relativevalue than in the case of the bright wire since the intrinsic elongationcharacteristics of this wire when uncorrugated are already appreciable.

However, the total elongation is greater for the annealed corrugatedwire than for the bright corrugated wire so that it allows a greaterexpansion than the corrugated bright wire, which corresponds to agreater ratio between the diameter of the socket of the pipe and thediameter of the body of the pipe.

The example described hereinbefore relates to a concrete pipe having acircular section. In the embodiment shown in FIG. 4, the invention isapplied to a pipe T having an oval section and a flat portion. Thereinforcement;C has a corresponding shape. This shape is applicable inparticular to concrete pipes-for drains.

The deformations (folds, sinuosities, loops, convolu' tions orcorrugations) can be in the plane of the lattice panel or project fromthis plane, that is, the deformations can be, in the bent reinforcementcage, in the theoretical surface similar to that of the tubular elementand passing through the longitudinal or generatrix wires, or projectinwardly or outwardly relative to this theoretical surface and orientedin any way.

Although specific embodiments of the invention have been described, manymodifications and changes may be made therein without departing from thescope of the invention.

Thus the invention is applicable not only to tubular elements but alsoto oval, elliptical or prismatic tubular elements, the reinforcementhaving an oval, elliptical or prismatic shape.

Having now described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A hollow tubular or like shape one-piece reinforcing lattice ofwelded metal wire-like members for use as a reinforcement in a concretepipe, said lattice comprising warp members and weft members, and havinga body portion of one diameter and asocket portion of a larger diameter,the warp members which define the body portion being work-hardened andof high strength, other warp members at one end of said lattice whichdefine said socket portion being formed of a material which is ductile,said ductile members being elongatable and stretchable to provide saidlarger. diameter socket portion.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO.3,871,410

DATED March 18, 1975 mvamrmsr Mauric FRANCOIS It is certttied'that errorappears m the ab0verdentrfied patent and that said Letters Patent arehereby corrected as shown below:

In THE HEADING:

Under Foreign Application Priority Data inser t;

March 22, 1968 France 144,908

Signed and sealed this 17th day of June 1975;

(SEAL) Attest:

C. IIARSIZALL DANN RUTH C. NASOIJ Commissioner of Patents AttestingOfficer and Trademarks

1. A hollow tubular or like shape one-piece reinforcing lattice ofwelded metal wire-like members for use as a reinforcement in a concretepipe, said lattice comprising warp members and weft members, and havinga body portion of one diameter and a socket portion of a largerdiameter, the warp members which define the body portion beingwork-hardened and of high strength, other warp members at one end ofsaid lattice which define said socket portion being formed of a materialwhich is ductile, said ductile members being elongatable and stretchableto provide said larger diameter socket portion.